The purpose of this study is to investigate the central nervous system development of infants exposed to cocaine in utero. Both cardiac and electroencephalographic indices of CNS development are being assessed at conceptual ages of 40, 48, and 56 weeks. Mother-infant interactions are also being observed to assess the contribution of this variable to postnatal changes in cardiac and EEG patterns. Mothers and their infants are recruited from area full-term newborn nurseries based on toxicology and self reports of cocaine use during pregnancy. Newborns are tested for cardiac reactivity to an auditory stimulus while still in the nursery. Infant cardiac and sleep EEG patterns are then assessed at the ARC at the specified follow-up ages. Mother-infant interactions are videotaped at 48 and 56 weeks during a face-to-face play interaction and during a feeding. Additional assessments of infant reactivity and temperament as well as maternal co-morbidity are collected by maternal questionnaire. The data for this study have not been analyzed at this time. Newborn assessments have been collected on 14 drug exposed and 13 control infants. Follow-up assessments have been completed on 7 drug exposed and 4 control infants. Two cocaine exposed infants and five control infants are still enrolled in the study.